<?php $view->extend('Site1Bundle::layout') ?>
<form action="<?php echo $view->router->generate('desc_edit', array('id' => $tree->getId())) ?>" method="post">
    <p>Содержимое: <input type="text" name="value" value="<?php echo $tree->getDescription() != null ? $tree->getDescription()->getValue() :
            ''?>" />
    <p><input type="submit" /></p>
</form>